The present invention concerns a method of monitoring filter components. The components are hollow and employed for filtering hot and dusty gases.
A hot-gas filter with tubes suspended from a perforated slab that divides the housing into an unfiltered-gas section and a filtered-gas section is known from German Patent 3 515 365. Unfiltered gas gets into the filtered gas when one of the tubes in this filter breaks and malfunctions. The whole filter has to be taken out of operation and the defective tube replaced to prevent too much dust and contaminants from getting into the filtered gas. The result is unnecessarily interrupted production.
The tubes in the filter housing disclosed in German OS 3 938 264, which is equivalent to European 0 433 637, are assigned group-by-group or row-by-row to individual headers that convey the filtered gas away. The ceramic tubes rest on or are positioned under the headers. The headers are distributed over the cross-section of the housing on one or more levels. The headers communicate with filtered-gas lines inside or outside the housing. There is also no way to handle the malfunctions that occur when one of these tubes breaks.
The ceramic tubes can be swept inside the housing of hot-gas filter known from German OS 3 938 264 (European 0 433 637) by injecting countercurrent bursts of a gas into the filtered-gas line. Measuring the pressure of the unfiltered gas and of the filtered gas to determine the difference is also known in this context (from U.S. Pat. No. 4,500,926). If the difference exceeds a prescribed threshold, a signal to sweep a specific group of filter components is emitted. The supply of unfiltered gas to that group is discontinued while it is being swept. The rate of flow of filtered gas through the header is measured and added to the difference that triggers the sweeping in another known approach (WIPO 88/07404). Even these techniques, however, reveal nothing about the state of a particular group of filter components in that the pressure and flow of the filtered gas is more or less determined from the gas leaving the housing.